Electric ignition system

ABSTRACT

The present fuel control and ignition system senses both the temperature of an electric igniter and flame at a burner. When the system senses that the igniter has reached ignition temperature, the main fuel valve is opened and the igniter deenergized. If ignition occurs, then the main fuel valve will be held open and the igniter deenergized until there is no more demand for heat, when the fuel valve will be closed. However, if ignition does not occur or if power is lost after a flame has been established at the burner, then the main fuel valve will be closed and the ignition sequence will be automatically restarted.

United States Patent Wolfe et al.

Jan. 8, 1974 Primary ExaminerEdward G. Favors Attorney-Anthony A. OBrien [5 7] ABSTRACT The present fuel control and ignition system senses both the temperature of an electric igniter and flame at a burner. When the system senses that the igniter has reached ignition temperature, the main fuel valve is opened and the igniter deenergized. If ignition occurs, then the main fuel valve will be held open and the igniter deenergized until there is no more demand for heat, when the fuel valve will be closed. However, if ignition does not occur or if power is lost after a flame has been established at the burner, then the main fuel valve will be closed and the ignition sequence will be automatically restarted.

11 Claims, 9 Drawing-Figures PATENTEDJAN M 3,784,351

SHEET 1D? 5 20 FIG. 2

PATENTED 81974 3,784,351

SHEET 2 0F 5 FIG. 3

FIG.4

PATENTEU 8W4 3,784,351

saw a or 5 20 FIG. 5

FIG. 6

PATENTE M BIBM 3.784351 SHEET 0F 5 FIG.8

PATENTEU 3784.351

SHEET 5 BF 5 FIG. 9

1 ELECTRIC IGNITION SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fuel control and ignition system for controlling a fuel burning apparatus. In particular the present invention relates to a system which will insure that a main fuel valve will be closed unless the igniter is at ignition temperature or flame is established in the burner.

2. Description of the Prior Art In any fuel burning apparatus it is important not to allow any build up of raw fuel in the burner when either the igniter is deenergized or no flame is present in the burner. This is particularly the case when a gaseous fuel and an electrical ignition means are used. Thus it is preferable if the system can be arranged to close the main fuel valve any time there is an interruption in power or the igniter is not at ignition temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved electric fuel control and ignition system which will prevent build up of raw fuel in a burner when an igniter is not at ignition temperatures or when no flame is established at the burner.

It is another object of the present invention to provide an improved electric fuel control and ignition system which will automatically gothrough an ignition sequence any time power is lost for even an instant or if the burner flame flame is extinguished for any reason.

It is also an object of the present invention to provide an electric fuel control and ignition system which senses the heat of either the igniter or the burner flame and closes the main fuel valve if insufficient heat is sensed. v

Yet another object of the present invention is to provide an electric fuel control and ignition system which relies upon open contacts for all safety features.

A further object of the present invention is to provide an electric fuel control and ignition system which is simple, reliable, failsafe and economical to build and operate.

A. still further object of the present invention is to provide an electric fuel control and ignition system which can be expanded to provide pressure regulation and have two valves in series for double safety.

The present electric fuel control and ignition system includes a thermostat, a radiant heat sensor, an electric igniter, and a fuel control unit having a main fuel valve. The radiant heat sensor is positioned to sense the temperature of the igniter and burner flame. A heat motor is connected to the radiant heat sensor and arranged to heat while the igniter is heating and enable opening of the main valve when the sensor detects that the igniter has reached ignition temperature; thereafter the main valve is opened and the heat motor and igniter are deenergized and the heat motor acts to lock the valve closed should the valve be deenergized even momentarily. If the sensor does not sense the presence of flame, the valve will close and be disabled by the heat motor while a reignition cycle is started.

BRIEF DESCRIPTION OF THE DRAWINGS The means for accomplishing the foregoing objects and other advantages and a fuller understanding of the invention will be apparent from the following specification taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic illustration, partially in section, of a first embodiment of the present invention shown in the off or deenergized condition;

FIG. 2 is a schematic illustration, partially in section, of a first embodiment of the present invention shown after the start of an ignition or heating sequence;

FIG. 3 is a schematic illustration, partially in section, of a first embodiment of the present invention shown after ignition and operating under normal conditions;

FIG. 4 is a schematic illustration, partially in section, of a first embodiment of the present invention shown immediately after an interruption of electrical power to the system;

FIG. 5 is a schematic illustration, partially in section, of a second embodiment of the present invention shown inv the off or deenergized condition;

FIG. 6 is a schematic illustration similar to FIG. 5 showing the second embodiment of the present invention after the start of an ignition or heating sequence;

FIG. 7 is a schematic illustration similar to FIG. 5 showing the second embodiment of the present invention after the igniter has reached ignition temperature;

FIG. 8 is a schematic illustration similar to FIG. 5 showing the second embodiment of the present invention immediately after a momentary interruption of electric power; and

FIG. 9 is a schematic illustration similar to FIG. 5 showing the second embodiment of the present invention after an interruption of electric power and in which the electromagnetic valve is stuck in the open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the first embodiment of the present electric fuel control and ignition system is shown in FIGS. 1 to 4. The system includes a gas control unit 10, which con trols flow of fuel from a source (not shown) to a burner 12 in furnace 14, an electric igniter 16 positioned in igniting proximity to the burner 12, a radiant sensor 18 positioned to. be responsive to heat from both the burner 12 and the igniter l6 and a thermostat 20.

The gas control unit 10 has a housing 22 with an inlet 24 connected to the source of fuel (not shown) and an outlet 26 connected to the burner. A chamber 28 is formed in the housing opening directly to the inlet.24. A conduit 30 connects the outlet 26 to the chamber 28 through valve seat 32. An electromagnetic valve 34 is mounted in the housing and includes frame 36 with coil 38 mounted thereon to control movement of armature 40. An L shaped lever 42 is mounted for pivotal movement on pivot 44 and includes integral first arm 46 and second arm 48. The first arm 46 passes through diaphragm seal 50 and is connected near its free end to armature 40 by pin 52. The second arm 48 has valve member 54 connected near its free end by pin 56 and spring 58 biasing the lever so that valve member 54 normally engages seat 32. A heat motor 60 is mounted on the housing 22 within cover 62. The heat motor is formed by a bimetal element 64 and a coil 66 mounted in cantilever fashion from frame 68. A spring arm 70 extends from the free end of the bimetal element and has a wedge 72 on its free end positioned to normally depend between the free end of the first arm 46 and frame 36.

The radiant sensor 18, as mentioned above, is positioned in the furnace 14 to be responsive to the heat of both the igniter 16 and the flame from burner 12. The sensor is formed by a bimetal element 74 which forms a movable contact between fixed contacts 76 and 78. The thermostat 20 is connected to the movable contact by line 80. Fixed contact 76 is connected to coil 38 of the electromagnetic valve by line 82 with the opposite side of the coil connected to a power source (not shown) by line 84. Fixed contact 78 is connected to igniter 16 by line 86 and to heat motor 60 by line 88. The opposite sides of the igniter and the heat motor are connected to the power source (not shown) by lines 90 and 92 respectively.

The operation of this first embodiment is as follows;

In the condition shown in FIG. 1 the system is cut off with thermostat 20 open, the radiant sensor positioned with the movable contact 74 contacting fixed contact 78, the igniter 16 deenergized, the coils 38 and 66 deenergized and the valve 34 closed.

When the thermostat 20 is closed to start a heat cycle, as shown in FIG. 2, several things start to happen at once. The igniter 16 is energized from a source (not shown) through the closed contact between movable member 74 and fixed contact 78 via lines 80, 86 and 90. At the same time the heat motor coil 66 is energized through the same closed contacts via lines 80, 88 and 92. The energized coil 66 will heatbimetal 66 causing the upward deflection of the arm '70 until wedge 72 is withdrawn from between arm 46 and frame 36 of the electromagnetic valve 34. The energized igniter 16 will increase in temperature until, asshown in FIG. 3, the radiant sensor 18 senses that ignition temperature has been reached and snaps to'the position with the movable member 74 contacting the second fixed contact 76. This actuation of the radiant sensor 18 causes the igniter 16 to be deenergized, the electromagnetic valve 34 to be energized and the heat motor 60 to be deenergized. Energization of the electromagnetic valve 34 will cause the valve member 54 to be moved away from the valve seat 32 against the bias of spring 58 and allow passage of gaseous fuel from the inlet 24 through chamber 28, conduit 30 and the outlet 26 to burner 12. Deenergization ofthe heat motor 60 will allow the bimetal 64 to coolreturning the arm 70 and the wedge 72 towards their original positions. However, the spring force of the arm 70 is not sufficient to overcome the magnetic force of the valve 34 since the arm is lightly loaded. Thus the system will remain in the operating condition as shown in FIG. 3.

If by chance the fuel flowing from burner 12 does not ignite, the igniter 16, which was deenergized when radiant sensor 18 sensed ignition temperature, will cool until no heat equal to ignition temperature is sensed by the radiant sensor 18 at which time the movable bimetal member 74 snaps back to engage the first fixed contact 78. This will also deenergize and close the electromagnetic valve 34 to stop the flow of gas and will start another ignition cycle by reenergizing the igniter l6 and heat motor 60. If proper ignition takes place then the conditions shown in FIG. 3 will remain.

If after proper ignition, there is a momentary interruption of electrical power to the system, then the electromagnetic valve 34 will be deenergized. When the valve armature 40 is released, the wedge 72 will move into position between arm 46 and frame 36, as. shown in FIG. 4, and will prevent the reopening of the valve until after the system goes through a complete reignition cycle. Thus even though the electric power is only momentarily interrupted and is instantly reestablished, the main fuel valve will still be closed and prevented from reopening until completion of an ignition cycle thus preventing any possibility of an excessive amount of fuel building up in the burner. When the main valve is closed, the radiant sensor will sense burner flame out and return to the position shown in FIG. 1 to enable the starting of the ignition cycle, which will commence automatically since the thermostat is still closed.

The second embodiment is shown in FIGS. 5 to 9 and those elements which are identical with the first embodiment are indicated by the same reference numerals. The primary difference in the two embodiments is the second embodiment includes a diaphragm valve controlled by a pilot regulator and a pilot valve. The housing 94 of the gas control unit 10a has an inlet 24 connected to a source of fuel (not shown) and an outlet 26 connected to burner 12. However, in addition to first chamber 28 there is a second chamber 96 formed intermediate valve seat 32 and conduit 30. The second chamber is connected to the valve seat 32 by second conduct 98 and to conduit by second valve seat 100. A diaphragm valve 1102 is mounted in second chamber and is normally biased against second valve seat 100 by spring 104.

A pilot valve 106 is mounted in a third chamber 108 and includes a valve member 110 biased by spring 112 to normally engage pilot valve seat 114. A valve stem 116 extends from valve member through diaphragm seal 118 and has pivoted actuator member 120 mounted on the free end thereof. Third conduit 122 extends from pilot valve seat 114 to chamber 96 on one side of the diaphragm and restricted fourth conduit 124 connects conduit 122 to second conduit 98 on the opposite side of the diaphragm.

Pilot regulator 126 is positioned in a fourth chamber 128 and includes a valve seat 130 and a valve member 132 adjustable with respect to the seat by screw means 134, spring 136 and diaphragm 138. A fifth conduit 140 connects the pilot regulator chamber to the pilot valve chamber and a sixth conduit 142 connects the pilot regulator chamber to the first conduit 30.

A second cantilever arm 144 extends from the heat motor 60 parallel to the first arm 70. A wedge 146 is mounted on the free end of arm 144 and normally is positioned between frame 36 and safety armature 148. The safety armature is normally biased to the position shown in FIG. 5 by spring 150. The safety armature is moved against the force of spring 150 by energization of coil 38. Arms 1152 and 154 depend from cantilevered arms 70 and 144, respectively, and are positioned to engage the pivoting pilot valve actuator member 120.

The second embodiment operates in a manner similar to the first embodiment and only the differences in operation will be discussed. Referring first to FIG. 5, the thermostat is shown open indicating no call for heat so that magnetic valve 34 is closed. The pilot valve 106 is also closed allowing the restrictive orifice 124 to equalize pressure on both sides of the diaphragm valve 108 thereby allowing spring 104 to close the diaphragm against valve seat 100. If the magnetic valve 34 leaks gas, the diaphragm valve 102 will remain closed thus preventing an unwanted build up of fuel at the burner.

Referring to FIG. 6 the control contact of the thermostat is shown closed calling for heat. The igniter 16 and heat motor 60 will be energized through the closed contract 74 and 78 of the radiant sensor 18. The heat motor coil 66 will heat bimetal 64 causing arms 70 and 144 to move upward. This movement will both remove the wedges 72 and 146 from locking the magnetic valve 34 as well as cause arms 152 and T54 to open the pilot valve 106 through engagement with actuator member 120. Gas flow will be prevented through the main valve at this time since the magnetic valve is still deenergized. I

The radiant sensor 18 is shown, in FIG. '7, after having sensed that the igniter l6 reached gas ignition temperature and the bimetal contact '74 having snapped to 1 make contact with fixed contact '76 to energize the electromagnetic valve 34 to open the main valve and allow gas to flow to the burner 12 where it is ignited by the igniter T6. The igniter l6 and the heat motor 66 are deenergized and the wedges 72 and 146 move down until stopped by the arm 46 and safety armature M6 of magnetic valve. The pilot valve 166 is held open and the pressure behind the diaphragm valve 162 is allowed to drop until the pilot regulator senses that the outlet pressure is at a preset value, at which time the pilot regulator I26 closes to maintain the outlet pressure at the preset valve. Gas will continue to flow through the open main valve and diaphragm valve as long as the radiant sensor 18 senses that a flame is present at the burner.

F IG. 8 illustrates the control system immediately after a momentary interruption of electrical power. The magnetic valve 34 and safety armature M6 are momentarily deenergized and the wedges 72 and 1146 move downward to block the valve and safety armature in their deenergized positions. Pilot valve 166 is also allowed to close so that pressure will again equalize on the diaphragm valve I02 which will be closed against is scat llilll by spring 104. Thus it is insured that the no fuel will flow to the burner allowing a dangerous buildup of fuel at the burner.

The second embodiment of the present invention is shown in FIG. 9 after an interruption of electrical power and with the magnetic valve stuck in the open position. In this case only the safety armature 146 is deenergized so that only wedge 146 moves down to a blocking position. This still allows the pivoting actuator member 120 of the pilot valve 106 to close the pilot valve thereby permitting pressure to equalize on the diaphragm valve 102 and close off the gas flow. When the radiant sensor 18 senses that no flame is present at the burner, the bimetal contact 74 will move to rest against fixed contact 78 and the conditions shown in FIG. 6 will exist for a normal reignition cycle.

The present invention has been described in detail with particular reference to twoembodiments thereof. However, it is to be understood that variations and modifications can be effected without departing from the spirit and scope of the invention. For example, a clapper type magnetic valve was used to illustrate the control principles although any valve construction which can be blocked in one position may also be used.

What is claimed is:

1. An electric fuel control and ignition system comprising fuel burner means,

radiant heat sensor means positioned to sense the temperature at said burner means and adapted to give a first output when the sensed temperature is below ignition temperature and a second output when the sensed temperature is greater than ignition temperature, electric igniter means in igniting proximity at said burner means and adapted to'be enabled by said first output,

valve means connected between a source of fuel and said burner means and including a movable means adapted to open in response to said second output from said radiant heat sensor means, and

blocking means adapted to move, during said first output, from a first valve opening preventing position to a second valve opening enabling position and, during said second output, to be biased towards said first position which is assumed upon closure of said movable means, said blocking means engaging said movable means to prevent opening of said movable means when said blocking means is in said first position. 2. An electric fuel control and ignition system according to claim ll wherein said valve means comprises an electromagnetic valve.

3. An electric fuel control and ignition system according to claim I wherein said valve means comprises an electromagnetic clapper type valve.

4. An electric fuel control and. ignition system according to claim 1 wherein said blocking means responsive to said radiant sensor outputs comprises a heat mo- UN.

5. An electric fuel control and ignition system according to claim li wherein said blocking means comprises coil means energized by said first output, bimetallic means mounted in cantilevered fashion and positioned to be heated by said coil, and

wedge means carried on the free end of said bimetallic means and adapted to block opening of said movable means in the cooled state of said bimetallic means.

6. An electric fuel control and ignition system according to claim 1 wherein said valve means comprises;

a housing having an inlet connected to said source of fuel and an outlet connected to said burner, a valve seat formed in said housing, a valve member adapted to engage said seat, means normally biasing said member against said seat, and electromagnetic means including a coil and an armature adapted to move said valve member, and

said blocking means includes wedge means adapted to prevent opening movement of said valve memher.

7. An electric fuel control and ignition system according to claim I further comprising:

pressure I responsive secondary valve means connected in series with said valve means.

8. A device for controlling flow of fuel to a burner in response to the temperature at said burner, said device comprising means for sensing the temperature at said burner and giving a first output indicating a temperature of less than ignition temperature and a second output indicating a temperature of at least ignition temperature,

normally closed valve means connected to feed fuel from a source to said burner and including a movable member,

valve actuating means responsive to said temperature sensing means and adapted to open said movable member when said second output is received,

blocking means responsive to a sustained period of said first output from said temperature sensing means for moving from a position engaging said valve actuating means and preventing opening of said movable member to a position enabling opening of said movable member, said blocking means being biased toward said engaging position during said second output such that said engaging position is assumed upon closure of said movable member and the movable member is prevented from opening until completion of a reignition cycle.

9. An electric fuel control and ignition system comprising a fuel burner means,

a bimetallic movable contact element positioned to sense the temperature at said burner means and connected to a source of power,

a first fixed contact for being engaged by said bimetallic element to produce a first output when the temperature at said burner means is below ignition temperature,

a second fixed contact for being engaged by said bimetallic element to produce a second output when the temperature at said burner means in above ignition temperature,

electric igniter means in igniting proximity at said burner means and adapted to be enabled by said first output,

valve means connected between a source of fuel and said burner means and adapted to open in response to said second output, and

blocking means adapted to move, during said first output, from a first valve opening preventing posiprising fuel bumer means,

radiant heat sensor means positioned to sense the temperature at said burner means and adapted to give a first output when the sensed temperature is below ignition temperature and a second output when the sensed temperature is not less than ignition temperature,

electric igniter means in igniting proximity at said burner means and adapted to be enabled by said first output,

primary valve means connected between a source of fuel and said burner means and adapted to open in response to said second output from said radiant heat sensor means,

blocking means adapted to move, during said first output, from a first valve opening preventing position to a second valve enabling position and, during said second output, to be biased towards said first position which is assumed upon closure of said primary valve means,

pressure responsive secondary valve means connected in series with said primary valve means, and

means for controlling operation of said secondary valve means including adjustment means for setting the pressure at which saidsecondary valve means opens.

11. An electric fuel control and ignition system according to claim 10 wherein said control means comprises,

pilot valve means, and

pilot valve regulator means.

* l l l= 

1. An electric fuel control and ignition system comprising fuel burner means, radiant heat sensor means positioned to sense the temperature at said burner means and adapted to give a first output when the sensed temperature is below ignition temperature and a second output when the sensed temperature is greater than ignition temperature, electric igniter means in igniting proximity at said burner means and adapted to be enabled by said first output, valve means connected between a source of fuel and said burner means and including a movable means adapted to open in response to said second output from said radiant heat sensor means, and blocking means adapted to move, during said first output, from a first valve opening preventing position to a second valve opening enabling position and, during said second output, to be biased towards said first position which is assumed upon closure of said movable means, said blocking means engaging said movable means to prevent opening of said movable means when said blocking means is in said first position.
 2. An electric fuel control and ignition system according to claim 1 wherein said valve means comprises an electromagnetic valve.
 3. An electric fuel control and ignition system according to claim 1 wherein said valve means comprises an electromagnetic clapper type valve.
 4. An electric fuel control and ignition system according to claim 1 wherein said blocking means responsive to said radiant sensor outputs comprises a heat motor.
 5. An electric fuel control and ignition system according to claim 1 wherein said blocking means comprises coil means energized by said first output, bimetallic means mounted in cantilevered fashion and positioned to be heated by said coil, and wedge means carried on the free end of said bimetallic means and adapted to block opening of said movable means in the cooled state of said bimetallic means.
 6. An electric fuel control and ignition system according to claim 1 wherein said valve means comprises; a housing having an inlet connected to said source of fuel and An outlet connected to said burner, a valve seat formed in said housing, a valve member adapted to engage said seat, means normally biasing said member against said seat, and electromagnetic means including a coil and an armature adapted to move said valve member, and said blocking means includes wedge means adapted to prevent opening movement of said valve member.
 7. An electric fuel control and ignition system according to claim 1 further comprising: pressure responsive secondary valve means connected in series with said valve means.
 8. A device for controlling flow of fuel to a burner in response to the temperature at said burner, said device comprising means for sensing the temperature at said burner and giving a first output indicating a temperature of less than ignition temperature and a second output indicating a temperature of at least ignition temperature, normally closed valve means connected to feed fuel from a source to said burner and including a movable member, valve actuating means responsive to said temperature sensing means and adapted to open said movable member when said second output is received, blocking means responsive to a sustained period of said first output from said temperature sensing means for moving from a position engaging said valve actuating means and preventing opening of said movable member to a position enabling opening of said movable member, said blocking means being biased toward said engaging position during said second output such that said engaging position is assumed upon closure of said movable member and the movable member is prevented from opening until completion of a reignition cycle.
 9. An electric fuel control and ignition system comprising a fuel burner means, a bimetallic movable contact element positioned to sense the temperature at said burner means and connected to a source of power, a first fixed contact for being engaged by said bimetallic element to produce a first output when the temperature at said burner means is below ignition temperature, a second fixed contact for being engaged by said bimetallic element to produce a second output when the temperature at said burner means in above ignition temperature, electric igniter means in igniting proximity at said burner means and adapted to be enabled by said first output, valve means connected between a source of fuel and said burner means and adapted to open in response to said second output, and blocking means adapted to move, during said first output, from a first valve opening preventing position to a second valve opening enabling position and, during said second output, to be biased towards said first position which is assumed upon closure of said valve means.
 10. An electric fuel control and ignition system comprising fuel burner means, radiant heat sensor means positioned to sense the temperature at said burner means and adapted to give a first output when the sensed temperature is below ignition temperature and a second output when the sensed temperature is not less than ignition temperature, electric igniter means in igniting proximity at said burner means and adapted to be enabled by said first output, primary valve means connected between a source of fuel and said burner means and adapted to open in response to said second output from said radiant heat sensor means, blocking means adapted to move, during said first output, from a first valve opening preventing position to a second valve enabling position and, during said second output, to be biased towards said first position which is assumed upon closure of said primary valve means, pressure responsive secondary valve means connected in series with said primary valve means, and means for controlling operation of said secondary valve means including adjustment means for setting the pressure at which said secondary valve means opens.
 11. An electric fuel control and ignition system according to cLaim 10 wherein said control means comprises, pilot valve means, and pilot valve regulator means. 